Caliper



May 5, 1925.

1,536,576 C. B. FIELDS CALIPBR Eil QJPJ-l l4 1 21 IN VEN TOR.

\ ATTORNEY.

. two plates 6 and 7 Patented May 5, 1925..

CARL B. FIELDS, OF 'SAN FRANCISCO, CALIFORNIA.

GALLPEB.

Application filed July 14, 1921.

To all whom it may concern I Be it known that I, CARL 13. Frame, acitizen of the United States, residing at San Francisco, in the countyof San Francisco, State of California, have invented a new and usefulCaliper, of which the following is a specification in such full andclear terms as will enable those skilled in the art to construct and usethe same.

This invention relates to a caliper and its object is to produce acaliper which will enable a workman to quickly determine the size of agiven rod he may be turning or operating upon without the necessity ofthe careful adjustment required with the ordinary form of micrometer andthis caliper is an improvement on the caliper shown in my Patent No.1,325,631, December 23, 1919.

A further object of the invention is to enable very close readings to betaken of different sized shafts or objects without the necessity ofmoving the micrometer gauge more than one turn to bring any given lineof th feeler gauge into alignment with the line for determining the sizeof the given object.

Another object of the invention is to simplify the construction and tomake a gauge which will be as small as is consistent with the work to beperformed by it.

Other objects of the invention will appear as the description proceeds.

An embodiment of the invention is shown in the accompanying drawings inwhich the same reference numeral is applied to the same portionthroughout, but I am aware that there may be modifications thereof.

Fig. 1 is a plan view of the complete gauge, and

Fig. 2 is a side elevation of the complete gau e. I

e gauge comprises a flat plate 1 having one end up-turned at 2 toreceive the slidable rod 3. At the opposite end of the plate itis'provided with two fingers 4 and 5. These fingers carry two plates 6and 7 which are secured thereto by means of suitable screws as indicatedat 8 and 9 and at one end of the small plates 6 and 7 there is a narrowlate 10 also connected to the plates 6 an 7.

The construction just outlined leaves an opening under the plate 10 andbetween the or a flat graduated slide Serial No. 484,561.

11. This slide has an operating handle 12 through which'the rod 3 passesand which is held in engagement with said rod with con siderable forceby means of a spring 13. The object of the spring 13 is to prevent theslide 12 from being easily dislocated from any given position on the rod3. However, when it is desired to move it it may be easily pushed backby the object itself or by the thumb if it is to be pushed forwardly.

The rod 3 has one end flattened and is provided with a slot throughwhich the screw 1% extends. At the other end the rod has a washer 15secured thereto and a stilf spring 16 placed between the washer 15 andthe lip-turned end 2 of the base 1. A knurled nut 17 is secured on theend of the rod 3 and the graduations thereon enable the operator to reada length equivalent to the space between one of the divisions of thescale on the blade 11, divided by the number of divisions on the knurlednut 17, the threads of the knurled nut being of such pitch as to shiftthe blade 11, one division of its scale with each turn of the knurlednut 17.

The top of the up-turned portion 2 of the plate 1 is provided with onemark with which the scale marks on the knurled nut are brought intoalignment when smaller gradnations than those shown on the slide 11 areto be read.

In operation the workman pushes the slide 12 outwardly with his thumband then presses the gauge into alignment with the object to bemeasured. At this time the knurled nut 17 is set at zero for conveniencein reading the amount; it may later have to be shifted to act as aVernier in reading the length the line 18 may be away from one of thegraduations on the blade 11. The result of this will be that the slide11 willbepushed back and the workman can read the size of the object byexamining the scale graduations on the slide 11, but inasmuch as thelines on the scale of the slide 11 will seldom coincide with the line 18the workman will ascertain the difference in thousands, the scale on theslide 11 usually being divided in fortieth parts, and the scale on theknurled nut is usually divided in twenty-fifth parts, by rotating thenut 17 to bring thelineoftho scale on the slide 11 which is immediatelybelow line 18 into'alignment with the said line 18. Inasmuch as theknurled nut 17 is usually set at zero this will at once give the numberof whole .divisions shown on the scale on the slide 11 plus thethousands read on the nut 17.

The spring 16 always holds the knurled nut 17 close y in engagement withthe upturned portion 2 so that it is particularly easy to read thatscale in conjunction with the line on the upturned plate 2. It will ofcourse be apparent that the distance apart of the marks on the slide 11will be determined by the size of the angle between the arms 4 and 5 butthis angle is ordinarily made such that the scale used can be divided toread fortieths of an inch directly on the blade 11 and then by dividingthe knurled nut 17 into twenty-fifths, thousandths can be easily read.

What I claim is as follows, but various modifications may be made in theconstruction shown in the drawings and above particularly describedform, within the purview of my invention:

1. In a caliper, a plate, a pair of diverging arms carried thereby, atone end thereof, a slide projectable between the arms and carrying aseries of graduations, a longitudinally slidable rod carried by theplate,

means frictionally connecting said slide androd for movement in unison,a micrometer nut having a series of graduations on its periphery andthreaded on said rod, and a spring holdingsaid nut in contact w1th anupturned portion of said plate there be ng reading lines on said platecooperatmg with the graduations on said slide and nut rethe graduationson said slide and nut respectively whereby the size of circular objectsmay be ascertained by moving the slide. 3. In a caliper, a plate havinga pair of diverging arms at one end, a slide projectable between thearms and carrying a series 5 of graduations, a threaded rod, meansmounting said rod for longitudinal movement along an axis coplanar withthe axis of movement of said slide, spring means frictionally connectingsaid slide and rod. a graduated micrometer nut threaded on said rod formoving the rod and slide and a spring on said rod urging said nut intocontact with an upturned portion of said plate, there being readinglines on said plate cooperating with the graduationson said slide andnut respectively whereby the size of circular objects may be ascertainedby moving the slide.

In testimony whereof I have hereunto set my hand this 30th day of June,A. D. 1921.

C. B. FIELDS. Witness:

A. G. BRUCE.

